Valve tappet



March 28, 1939. J L T L 2,152,404

VALVE TAPPET Filed June 18, 1958 INVENTOR TTORNEY8.

Patented Mar. 28, 1939 PATENT OFFICE VALVE TAPPET Joseph L. Dostal, Birmingham, Mich., asslgnor to Eaton Manufacturing Company,

Cleveland,

Ohio, a corporation of Ohio Application June 18, 1938, Serial No. 214,493

Claims.

This invention relates to valve tap-pets for internal combustion engines and particularly to that type of such tappets commonly known as barrel tappets, the principal object being the 5 provision of a generally improved tappet of this type that is light in weight, economical to produce and efficient in operation.

Other objects of the invention include the provision of a one-piece hollow barrel type valve ially spaced solid transverse walls one of which constitutes the bottom face of the tappet and the other of which is located intermediate the opposite ends of the tappet whereby to form a recess in the upper ends of the tappet for reception of a push rod or the like; the provision of a barrel type valve tappet of one-piece cast construction including a pair of solid transverse walls interconnected by a cylindrical wall provided with windows therethrough, the lower of such walls constituting one end surface of the tappet and such end surface being of a chilled character, the other of said transverse wall being located intermediate the length of the tappet in its upper face for reception of a push rod or the like; the provision of a one-piece hollow barrel type valve tappet having windows therein and in which the margins of the windows are outwardly beveled; the provision of an integral hollow barrel type valve tappet of the type adapted to receive a push rod so constructed and arranged as to provide a relatively soft wall for reception of an end of the push rod and a second wall having a hardened face for contact with a valve operating cam; and the provision of a tappet of the character described in which the push rod receiving recess is provided with axially directed ribs or webs for guiding the lower end of a push rod into the pocket formed centrally therein for receiving the same.- 7

The above being among the objects of the present invention the same consists in certain novel features of construction and combinations of parts to be hereinafter described with reference to the accompanying drawing, and then claimed, having the above and other objects in view.

In the accompanying drawing which illustrates a suitable embodiment of the present invention and in which like numerals refer to like parts throughout the several different views,

Fig. 1 is a side elevational view of my improved tappet;

Fig. 2 is a verticalsectional view taken axially tappet of cast construction having a pair of ax-' and being provided with a machined depression (Cl. 123-90) {iii through the valve tappet shown in Fig. 1, as on the line 2-2 thereof;

Fig. 3 is a transverse sectional view taken on the line 33 of Fig. 1; and,

Fig. 4 is a transverse sectional view taken on the line 44 of Fig, l.

The present invention relates to valve tappets of the so called barrel type for internal combustion engines and particularly to those types of barrel type tappets adapted to work between a valve operating cam and a push rod such as is employed in overhead valve types of internal combustion engines. Such tappets are called barrel type tappets for the reason that they are of a cylindrical nature and usually of substantially uniform diameter throughout their length and do not have an enlarged head as in the socalled mushroom type of tappets. Furthermore the present invention relates to such tappets when formed of cast construction, particularly when formed of cast iron as is the common practice in order to enable that face of the tappet adapted for engagement with the valve operating cam to be formed of chilled cast iron to enable it to withstand the wearing action of the cam thereon.

In the past this type of tappet has been formed generally in the shape of a deep cup, in other words as a cylindrical body one end only of which is closed. In such case the outer face of the closed end is chilled as above described and the inner face of such end is generally provided with a depression for reception of the lower end of the push rod. Difficulties have occurred in connection with such constructions in the past due to the reason that it is usually desirable to provide as deep a chill as is reasonably possible in quantity production for the chilled face of the tappet and because it is necessary to machine the depression on the inner face of such end for reception of the push rod. Unless the end wall was made of a thickness totally unnecessary from the standpoint of structural strength the tool employed for machining the depression often penetrates to the chilled portion of the end wall and its cutting edge is thereby destroyed, and the tappet then being substantially unmachinable from a practical standpoint must be scrapped and, therefore, represents a loss.

The difficulties encountered in connection with the above described conventional types of barrel type valve tappets of cast construction adapted for the reception of push rods is eliminated .by the use of the present invention. This is ac= complished by providing the valve tappet with two axially spaced solid transverse walls, one of which is located at the extreme end of the tappet and, therefore, corresponds with the end wall conventionally provided, and the other of which i is located in axially spaced relation thereto whereby in the formation of the tappet the presence of any chilled iron in this second wall is entirely eliminated and, accordingly, it may be readily machined without unnecessarily endangering the cutting edges of the tools so employed. In accordance with the present invention this. second transverse wall is provided intermediate the ends of the tappet whereby the upper portion of the tappet is of more or less cup-shaped conformation but of less depth than would be in the case of a tappet constructed in accordance with conventional practices and of the same length, such cup serving, of course, for reception of the lower end of a push rod. In order to lighten the weight of the tappets produced in accordance with the present invention, as well as to provide for the support of internal cores during the casting operation, that portion of the tappet intermediate the transverse walls: is provided with one or more windows in its side walls, and the material of the side walls extending around the margins of the openings is preferably beveled so as to eliminate the possibility of any sharp cutting edges at the margins of the windows which might serve to cut away the film. of lubricant in the bore provided in the engine for its operation.

Referring now to the accompanying drawing the. embodiment of the present invention shown by way of illustration is of generally cylindrical conformation externally. As best illustrated in Fig. 2 it includes a solid circular bottom wall l and a solid or substantially solid circular transverse wall I 2 located intermediate the opposite ends of the tappet. The tappet is hollow between the walls l0 and I2 and the hollow cylindrical I walls I interconnecting the walls I!) and I2 are provided with a plurality, shown by way of illustration as four, preferably equally angularly spaced windows l6 therethrough. Those portions of the side walls l4 forming the margins of the openings l6 are preferably rounded or beveled away as at l8 so that, as best illustrated in Fig. 2, the provision of the windows I6 doesnot provide sharp cutting edges exposed at the outer surface of the tappet and which if provided would tend to cut away the film of oil provided for lubricating purposes in the bore of an internal combustion engine formed to receive and guide the tappet in its reciprocatory movement during op- 1 eration of the engine.

. cular pocket or depression 20 for reception of the lower end of a conventional valve push rod (not shown). Additionally the inner surfaces of the side walls of the tappet above the transverse wall l2 are preferably provided with a plurality of .preferably equally angularly spaced longitudinally extending inwardly projecting ribs or webs 22 the lower ends of which preferably merge into the outer margin of the pocket 20 and the upper ends of which preferably merge into such inner surfaces, the webs or ribs 22'serving the purpose of guiding'the lower endof the push rod inserted into the upper end of. the tappet centrally thereof and into the pocket 20 during assembly of the push rod to the tappet.

It. will be-noted that the-axially outer portion of the end wall l0 comprises a relatively thick layer '24 of chilled cast iron, this being provided in accordance with conventional practice by employing a chill plate for closing the corresponding end of the mold in which the tappet is produced. The transverse wall I2 is preferably formed during the casting operation without the use of chill plates or the like and, accordingly, is of uniform and relatively soft or at least readily machinable character throughout. Consequently the pocket 20 may be machined in the wall l2 without danger of striking a chilled portion of the tappet and the presence of the chilled layer 24 offers no problems whatever as far as the machining of the pocket 20 is concerned. Accordingly the necessity of scrapping the tappets because of too great a depth of the chill in the cam engaging wall thereof is entirely eliminated by the use of the present invention. Inasmuch as the side wall portions of the tappet above the transverse wall l2 are preferably imperforate the upper end of the tappetforms a cup for reception and collection of anample supply of lubricant between the lower end of the push rod and the tappet and consequently the side walls of the tappet below the transverse wall l2 may be cut away to form the windows I6 and thereby lighten the construction without effecting proper lubrication of any of the wearing surfaces of the tappet in any respect whatever.

The tappet shown is relatively light, relatively economical to both cast and machine, it eliminates certain machining problems existent in connection with conventional forms of tappets of. this'type and is efficient in operation.

Formal changes may be made in the specific embodiment of the invention described without departing. from the spirit. or substance of the broad invention, the scope of which is commensurate with the appended claims.

What I claim is:

l. A one-piece hollow barrel type valve tappet of cast construction comprising a hollow cylindrical body, a solid wall closing one end of said body, a second solid Wall extending transversely of said body intermediate the ends thereof, said body intermediate said walls being provided with windows therethrough, and that end of said body opposite the first mentioned wall being opened.

2. A one-piece hollow cast barrel type valve tappet comprising a pair ofaxially spaced solid transverse walls, a hollow body portion interconnecting said walls and provided with windows therethrough, and a hollow body portion extending outwardly beyond one of said transverse walls with respect to the-first mentioned body portion whereby to provide a cup-shaped recess inv the corresponding end of said-tappet.

3. A one-piece hollow cast barrel type valve tappet comprising, in combination, a hollow cylindrical body portion, a solid transverse wall closing one end of said body portion, a second solid transverse wall intermediate the ends of said body portion, that surface of the first mentioned transverse wall on the side thereof opposite the second mentioned transverse wall being of rela tively hardand unmachinable'character, said body portion intermediate said wall being windowed, and that portion of said body portion extending beyond said second mentioned transverse wall onthe side thereof opposite the first mentioned transverse wall being substantially imperforate.

4. A one-piece hollow cast iron barrel type valve tappet comprising, in combination, a substantially cylindrical hollow body portion, a solid transverse wall closing one end thereof, a second transverse wall intermediate the opposite ends of said main body portion, said second transverse wall having a pocket formed in that surface thereof more remote from the first mentioned transverse wall, and ribs formed internally of said main body portion axially beyond the pocketed surface of said second transverse wall serving as means to guide a push rod into said pocket.

5. A one-piece hollow cast iron barrel type valve tappet comprising, in combination, a hollow cylindrical body portion, a solid transverse wall closing one end of said body portion and having a hard and substantially unmachinable outer face, a substantially solid second transverse wall portion located intermediate the ends of said main body portion, said main body portion between said transverse walls having windows formed therein and being inwardly beveled about the margins of said openings, that surface of said second mentioned transverse Wall opposite the first mentioned transverse wall being formed to provide a pocket centrally thereof, and a plurality of ribs formed upon the inner surface of said main body portion axially outwardly beyond said pocketed surface of said second transverse wall for guiding a push rod into said pocket.

JOSEPH L. DOSTAL. 

